Radiobiologia, radiotherapia最新文献

Between 1982 and 1987 we carried out a prospective randomized study to compare the effectiveness of high-dose half-body irradiation (HBI) (A), intensive combined chemotherapy (B), and local or locoregional radiotherapy (C) in the therapy of extended small cell lung carcinoma (SCLC). 99 patients with a histologically proved SCLC were assigned to the three therapeutic groups of series: A = 31 patients, B = 37 patients, C = 31 patients. The median survival period showed a statistically significant advantage (p less than 0.01) for the chemotherapy group (B = 46 weeks) versus the two radiotherapy groups (A = 19 weeks, C = 23 weeks). The survival after half a year, one year, and two years also gave a clear advantage for the chemotherapy group. No difference was found between the radiotherapy groups A and C. The high-dose HBI gave no improvement of the sad therapeutic situation for the extended SCLC.

Adult Swiss albino mice were exposed to 4.5 Gy, 9.0 Gy and 12.0 Gy of 60Co gamma rays and post-irradiation variations in the crypt cell population of jejunum were studied. In all the three exposure groups, a significant decrease in cellularity was observed on day 1. With the beginning of recovery crypt cell population tended to increase and gradually approached normal value by day 8 and 14 in mice exposed to 4.5 Gy and 9.0 Gy respectively. In mice exposed to 12.0 Gy normal value was never attained.

Surgery and radiotherapy complete each other in local control of suffering from rectal carcinoma. A radiotherapeutic effect on tumor is secured often. The adjuvant radiotherapy is the most interesting indication, though the most controversial as present too. Analysing all data and with experiences of an own irradiation study we have not any doubt that the indication is qualified for a combined therapy, if the therapeutic aim with priority is to prevent a local relapse as the most frequent and complained of form of therapeutic failure. In this problem, radical irradiation forms, as pre- and accumulating irradiation (sandwich-technique) and after-irradiation, render superior to an exclusive pre irradiation. In result of this study we practise a preirradiation of 25 Gy with immediately following operation and an accumulating irradiation to 50 Gy in proved high-risk-stage (T greater than or equal to 3 NoMo,Tx N1-3 Mo). If there is a primary local incurability by tumor invasion into the neighbourhood a pre-irradiation is done with 50 Gy and following explorative laparatomy within 4-6 weeks. Nearly 60% of these tumors become operable after that. Likewise we practise in unirradiated patients with locoregional tumor recurrence. Also here the extirpation quota of patients with general or systemic incurability, that a stoma construction is required in, we carry out a transanal tumor reduction and irradiate with 50 Gy after that. Especially this therapeutic principle has proved its worth in patients that are past eighty. Here with acceptable living quality and avoiding a stoma construction a survival can be reached that corresponds to the statistical survival of this stage of life.

In 90 patients with malignant neoplasia of larynx, stomach and cervix uteri the functional state of hemostasis was investigated within the process of radiotherapy and in radiotherapy and radiosensitization by metronidazole. Aim of this work is to answer the question if metronidazole affects the state of organism besides its effect on radiosensitivity of tumor tissue, especially the system of hemostasis, the impairment of which can not seldom result in thrombohemorrhagic complications in oncologic patients as is known. It was pointed out that the thrombophilic status of the blood of patients with stomach carcinoma continues to be unchanged and the patients are endangered for thrombosis potentially. In consequences of radiotherapy and doses of metronidazole the capacity for adhesion is decreased in thrombocytes of patients with laryngeal and cervical carcinomas to a high degree, whereby the thrombogenic potential of blood is reduced and with that the risk for origin of intravascular thrombosis.

Female mice (CBA X C57 Bl) F1 were exposed a single total-body gamma-irradiation with a dose efficiency of 6.5 Gy/min with doses of 2.5-7.5 Gy in air or inhaling a gas mixture of 6-6.5% oxygen and 94-93% nitrogen. All naturally died animals were examined pathoanatomically. By means of the rate of cardio- and nephroscleroses a protective effect of hypoxia was found with a dose modification factor of 1.5. Dynamics and degree of intensity of a radiogenic pneumosclerosis were studied by means of a stereologic analysis 3, 6, and 12 months after a single roentgen irradiation of the right thorax half of rats with a dose efficiency of 2.2 Gy/min with doses of 10, 14.3, 20 Gy in air and 14.3 and 20 Gy inhaling a gas mixture with 10% oxygen and 90% nitrogen. Applying the criterion of accumulation of connective tissue within the irradiated lung the protecting effect of hypoxia was estimated according to the dose modification coefficient, that varied in a range of 1.0-1.64.

In conventional radiobiology the survival fraction of cell cultures in the exponential phase is observed by the colony-forming ability, and the linear-quadratic model represents an adequate frame of the numerical adaptation. The measurement of the ATP-concentration of L 1210 cells by 31P-NMR-spectroscopy in dependence of the applied radiation dose can also be used to evaluate dose-response relationships. In particular, the beta-peak of the ATP is suitable to seize the chronological behavior of the cellular ATP-concentration. An access to RBE of a radiation quality is obtained by monitoring the ATP-concentration, and the combination treatment (irradiation and incubation of cisPlatinum) has also been studied with regard to the question of synergistic interactions.

Starting from different definitions of the term "radiation injuries" published in literature considerations are made to term of injury in medicine generally and in radiotherapy particularly. It is suggested to use the term "radiogenic injury of health" instead of the term "radiation injury" and to speak of "complications in connection with medical application of rays" before causal explanation of the state of affairs.

Resulting from statements recorded in law directions of the GDR to the duty in profession of a physician and to restitution in injuries of health in consequence of breach of these duties experiences are reported that were collected with the report of complications in connection with medical use of radiation in almost 20 years. As a conclusion it is referred to data and discharge material that is necessary to reconstruct the irradiation. Report and quality criteria are specified exemplarily, that belong to a commentary to directives for reports num. 11 and, partly deduced from it, to directives for radiotherapy, came into force in 1986. Some casuistic contributions complete the representations.

A radiobiological model is represented, that allows to estimate the number of surviving tumor cells at the end of radiotherapeutic series with equivalent NSD. On this base a programme for computer-assisted calculation was elaborated. The programme allows to estimate optimal conditions of dose fractionation, in which a devitalization of a maximum number of tumor cells is guaranteed. For the radiotherapy of radioresistant tumors, characterized by the extrapolation number n greater than 2, optimal parameters can be obtained by means of simple mathematical formulas. The elaborated model allows to increase the efficiency in radiotherapy of malignant tumors with known radiobiological parameters.

Starting from the chain of single steps in radiotherapy, the requirements of topometrical treatment planning are defined and current directions of development for the improvement of accuracy and clearness of treatment plans are shown. By far not all the possibilities of ultrasound tomography (UST) and NMR-tomography for use in radiotherapy have been clarified up to now. Particularly in case of UST the range of application in radiotherapy can be essentially widened due to technical developments. Computerized tomography (CT) today holds a very important place in radiotherapy. In the centre of current interest are simulators able to produce CT and computerized tomographs with the possibility to use them as simulators. Pinpointing some of such developments, the importance of three-dimensional treatment planning with its diverse possibilities is detailed. They put the physician and the physicist in a position to imagine and to interpret quickly and effectively the enormous variety of data in treatment planning.